package org.liufeng.course.util;

 

import java.security.MessageDigest;

import java.security.NoSuchAlgorithmException;

import java.util.Arrays;

 

/**

 * 请求校验工具类

 *

 * @author liufeng

 * @date 2013-05-18

 */

public class SignUtil {

    // 与接口配置信息中的Token要一致

    private static String token = "weixinCourse";

 

    /**

     * 验证签名

     *

     * @param signature

     * @param timestamp

     * @param nonce

     * @return

     */

    public static boolean checkSignature(String signature, String timestamp, String nonce) {

        String[] arr = new String[] { token, timestamp, nonce };

        // 将token、timestamp、nonce三个参数进行字典序排序

        Arrays.sort(arr);

        StringBuilder content = new StringBuilder();

        for (int i = 0; i < arr.length; i++) {

            content.append(arr[i]);

        }

        MessageDigest md = null;

        String tmpStr = null;

 

        try {

            md = MessageDigest.getInstance("SHA-1");

            // 将三个参数字符串拼接成一个字符串进行sha1加密

            byte[] digest = md.digest(content.toString().getBytes());

            tmpStr = byteToStr(digest);

        } catch (NoSuchAlgorithmException e) {

            e.printStackTrace();

        }

 

        content = null;

        // 将sha1加密后的字符串可与signature对比，标识该请求来源于微信

        return tmpStr != null ? tmpStr.equals(signature.toUpperCase()) : false;

    }

 

    /**

     * 将字节数组转换为十六进制字符串

     *

     * @param byteArray

     * @return

     */

    private static String byteToStr(byte[] byteArray) {

        String strDigest = "";

        for (int i = 0; i < byteArray.length; i++) {

            strDigest += byteToHexStr(byteArray[i]);

        }

        return strDigest;

    }

 

    /**

     * 将字节转换为十六进制字符串

     *

     * @param mByte

     * @return

     */

    private static String byteToHexStr(byte mByte) {

        char[] Digit = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

        char[] tempArr = new char[2];

        tempArr[0] = Digit[(mByte >>> 4) & 0X0F];

        tempArr[1] = Digit[mByte & 0X0F];

 

        String s = new String(tempArr);

        return s;

    }

}
